Abstract
Even though the persistence length of double-stranded DNA plays a pivotal role in cell biology and nanotechnologies, its dependence on ionic strength lacks a consensual description. Using a high-throughput single-molecule technique and statistical physics modeling, we measure in the presence of monovalent (, , ) and divalent (, ) metallic and alkyl ammonium ions, over a large range . We show that linear Debye-Hückel-type theories do not describe even part of these data. By contrast, the Netz-Orland and Trizac-Shen formulas, two approximate theories including nonlinear electrostatic effects and the finite DNA radius, fit our data with divalent and monovalent ions, respectively, over the whole range. Furthermore, the metallic ion type does not influence , in contrast to alkyl ammonium monovalent ions at high .
- Received 28 September 2018
DOI:https://doi.org/10.1103/PhysRevLett.122.028102
© 2019 American Physical Society